Built on success in evaluating the wheat germ-expressed Pfs230 domains, recombinant Pfs230 domains were also expressed in P. pastoris and E. coli. Antisera raised against these domains demonstrated potent transmission blocking activities in an ex vivo standard membrane feeding assay, in a complement-dependent manner. Current efforts are focused on generating an effective production clone for preclinical development. The product will be combined with Pfs25, a lead transmission blocking vaccine candidate to form an effective combination vaccine.